Gm May Ax Plastic For Its Apvs

DETROIT — Lower steel prices and new technology could lead to changes in the manufacture of General Motors' front-wheel-drive minivans in the years ahead, but answers are coming soon.

GM will decide late this year or early in 1993 if the versatile vehicle's exterior will remain plastic, be switched to steel or become a steel-plastic hybrid, according to Donald Runkle, vice president of advanced engineering.

The minivans - the Chevrolet Lumina APV, Oldsmobile Silhouette and Pontiac Trans Sport - are assembled in North Tarrytown, N.Y., at the industry's oldest factory. North Tarrytown is one of the plants GM has said it will close.

It is believed that a materials selection change could come as production of the minivan is shifted from the plant on the banks of the Hudson not far from Manhattan.

Runkle's remarks, and warm comments about steel, came after he spoke at the annual technical conference of the Society of Plastics Engineers in Detroit.

Runkle said the exterior of the minivan has earned compliments, but he made it clear a change is possible.

There's no question about the body material for Chevrolet Corvettes, Runkle said: ''Corvette is still plastic and will stay plastic.''